• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

EAR 834P needing repair

I have an EAR 834P that has developed distortion on the left channel. It only occurs on certain relatively high frequency sounds. I've replaced the tubes but that didn't help.

Anyone able (and willing) to help me fix it? If anyone had a schematic they'd be willing to share, that would be a good start.

Based on my experiences (not with EAR, but with commercial audio components in general), I'm not very enthused about sending it to a dealer for repair. If I cannot fix it, I'll probably build a solid state phono preamp (maybe the PhonoClone).



2007-05-07 10:11 pm
As I recall the amp runs into HF-oscilation with the wrong tube in V3 position.
I would go for a low transconductance type like ECC82/12AU7 here.
You may also need to try different manufacturers, there is a large spread of various constructions around the ECC82 .
A broken wire or bad solder joint between the jacks and the board maybe? Does yours have the built in SUTs? Maybe the MM MC switch is dirty.

Every tube is shared between both channels. It's not unknown for the two haves to age differently but not likely that only one side would go real bad.

Remove and reinstall all of the tubes 3 or 4 times. Might be a dirty connection between tubes pins and socket.